Kohler, G. and Milstein, C. (Nature 83:405-414 (1975)) described a technique for the production of antibodies of defined and predictable specificity by fusing spleen cells and myeloma cells. Recently, the importance and use of these monoclonal antibodies in biotechnology has dramatically increased. Their use has shown promise for the improvement of immunoassay sensitivities (Dalesevier et al., Clin. Chem. 27:1797-1806 (1981)). In addition, they are of great interest in the "missile therapy" field (Lessermann et al., Nature 293:226-228 (1981); Blythman et al., Nature 290:145-146 (1981), whereby drugs, such as anti-cancer agents, may be coupled to monoclonal antibodies which then specifically attack target cells (e.g., tumor cells) where they release the drug in situ. Much research dealing with the large scale production of monoclonal antibodies has been reported in recent years. However, antibody productivity by the fused cells or hybridomas is very low because of the slow growth or low secretion rate of the cells in culture medium. In the last 10 years, many reports detailing various methodologies for increasing monoclonal antibody productivity has been published. For example, electrical stimulation has been applied to hybridoma cells to activate metabolic activities and increase the monoclonal antibody production (Suzuki et al., Biochemica et Biophysica Acta 889:149-155 (1986). Factors have been described to enhance fusion of lymphocytes by mitogen stimulation of cells prior to fusion. Andersson and Melchers, Curr. Top. Microbiol. Immunol. 81:130-139 (1978) reported that after lipopolysaccharide (LPS) stimulation of mouse spleen cells, large blast cells fuse at least 10 times more frequently than the remaining small resting B cells.
N,N-dimethylglycine (DMG), which is a tertiary amino acid, is an intermediary metabolite found in low levels in many foods. It is produced in the body from choline and has been used as a non-fuel nutrient. In 1972, a report in the Russian veterinary medicine literature (Nizametidinova, G. A., Reports of the Kazan Veterinary Institute 112:100-104 (1972)) suggested that calcium pangamate was extremely effective in restoring immune competence to particulate antigen in X-ray irradiated guinea pigs and rabbits. Subsequent attention focused on DMG, a hydrolysis product of pangamic acid. DMG has been shown to be an effective modulator of the immune response in humans, by stimulating both humoral and cellular immunity (Graber et al., J. of Infect. Dis. 143:101-105 (1981)). In a double-blind study, human volunteers who received 120 mg of DMG (as the hydrochloride) orally per day demonstrated a four to five-fold increase in antibody production to the pneumococcal vaccine Pneumovax.RTM. as compared with controls. The test group also had increased production of leukocyte inhibition factor, which indicated enhanced cellular immunity to vaccine antigen.
Previous studies in our laboratory by Reap and Lawson (personal communication), who investigated the ability of rabbits fed DMG to respond to different antigenic stimuli showed that DMG can stimulate both the humoral and cellular immune systems in rabbits.